174 
were brown, yellow, and topaz-colonred; 
thers were greyish white, like pearl- 
stones, with the translncence and lustre of 
porcelain; and others still limpid, like 
flint glass, or in some cases like hyalite or 
precious opal, but withont the iridescence 
of the latter. I detached some of the 
globules, and firmly bedding them in a 
handle of wood, tried their hardness and 
firmness ; they bore strong pressure with- 
out breaking, and easily scratched not 
only flint-glass but window-glass, and even 
the hard green variety whicl/ forms the 
aquafortis-bottles. ‘Vhe globules which 
had acquired this extraordinary hardness 
were formed from plumbago, which was 
so soft that it was perfectly free from re- 
sistance when crushed between the thumb 
and finger.” Speaking of the globules 
obtained in another experiment, he ob- 
serves, that ‘‘ some were perfectly limpid, 
and could not be distinguished by the eye 
from portions of diamond.” The expe- 
riments detailed remove every suspicion 
which might be entertained that ‘these 
globules were the earthy matter contained 
in the plumbago, which was vitrified by 
the intense heat. They were exposed in 
a jar of oxygen gas to the focus of a 
powerful lens; and, although they neither 
melted nor altered their forms, a decided 
precipitate was formed upon the intro- 
duction of lime water into the vessel. The 
globules of melted plumbago are absolute 
non-conductors of electricity; as strictly 
so as the diamond.” 
Mr. Faraday, of the Royal Institution, 
has made the important discovery of a 
method, by which carbonic gas can be 
condensed, and exhibited in a liquid form, 
limpid and colourless like water: he has 
also effected the same thing with the 
following aériform substances, viz. nitrous 
oxide, sulphurous acid, sulphuretted hy- 
drogen, cyanogen and euchlorine, all of 
which, except the last, produce colourless 
fluids; that of chlorine being of a yellow 
colour. Mr. Faraday’s mode of*operating 
has been published, but only briefly, with 
regard to chlorine, and a repetition thereof 
by Sir H. Davy, with respect to muriatic 
acid ; it appears to consist, in causing the 
gases to he evolved from substances con- 
taining them, in hermetically sealed glass 
tubes, when the pressure of the atmos- 
phere of evolved gas occasions its con- 
densation into a fluid. 
The same thing has been effected, by 
mechanically forcing the gasses into a 
strong vessel, immersed in a frigorific 
mixture. Upon dividing a tube contain- 
ing fluid chlorine, a report was heard, the 
yellow fluid instantly disappeared, and a 
strong atmosphere of chlorine gas was 
Report of Chemistry and Experimental Philosophy. 
[Sept. i, 
produced. The fluids resulting from the 
other condensed gases, seem also ex- 
tremely volatile, and alike incapable of 
being retained at the ordinary tempera- 
ture and pressure of the atmosphere. — 
Is it too much to hope and expect, that ¢ 
ere long our ingenious chemical philoso- 
phers, will devise methods, by which the 
fluids thus obtained, can be further con- 
densed into solid or crystallized sub- 
stances? and thus the diamond be manu- 
factured, solid oxigen exhibited, &c. &e. 
A new and powerful galvanic appara- 
tus has been constructed at the London 
Institution by W. H. Pepys, esq. It 
consists of a single sheet of copper and 
one of zinc, each fifty feet long, and two 
feet broad. They are wound round a 
wooden centre, and kept apart by pieces 
of interposed hair-lines. The coil and its 
counterpoise are suspended bya rope over 
a tub of diluted acid. When lowered 
into the tub, its electricity is so low, as 
not to affect the electrometer; even a bit 
of charcoal serves to insulate it, and it can 
hardly ignite an inch of platinum wire of 
one-thirtieth of an inch diameter; but 
when the poles are connected bya copper 
Wire, one-eighth of an inch diameter, and 
eight inches long, it becomes hot, is most 
powerfully magnetic, and admirably adapt- 
ed for all electro-magnetic experiments, 
Indigo has lately been submitted to a 
rigid analysis by Mr. WALTER CRuM, of 
Glasgow, whose experiments are detailed 
in the “ Annals of Philosophy ;” whereby 
it appears, that sublimed or purified indigo 
is composed of one atom of azote, two 
atcms of oxygen, four atoms of hydrogen, 
and sixteen atoms of carbon; and in the 
course of these experiments he was fortn- 
nate enough to discover two new sub- 
stances allied to indigo: one of them, 
named by him phenicin, consisting of the 
above elements of indigo, combined with 
two atoms of water (or of its component 
gases); and the other, which he calls 
cerulin, consisting of the same elements of 
indigo, combined with four atoms of wa- 
ter (or its gases). Cerulin, in combina- 
tion with the sulphuric salts, is found by 
Mr. C. to possess the singular property of 
being soluble in pure or distilled water, 
but not so in impure water, of any kind 
which he tried ; and hence he explains the 
practice of many experienced laundresses, 
who, in the washing of printed dresses, 
particularly those whose colours are dark, 
have found it necessary to rince them in 
hard water (or else in salted or alumed 
water instead,) before hanging them up to 
dry, otherwise the colours run or spread 
on to the white parts. 
MONTHLY 
